In 1983, Pioneer 10 became the first man-made object to leave our Solar System.
Launched on March 2nd, 1972, Pioneer 10 was the first spacecraft to travel through the Asteroid belt and the first spacecraft to make direct observations and obtain close-up images of Jupiter. Pioneer’s last, very weak signal was received on January 23rd, 2003.
Learn more at http://www.nasa.gov/centers/ames/missions/archive/pioneer.html